Wine chemistry

• Acids in wine
• Phenolic compounds in wine
• Proteins in wine
• Sugars in wine
• Yeast assimilable nitrogen
• Minerals
• Dissolved gas (CO₂)
• Monoterpenes[1] and sesquiterpenes[2] such as linalool and α-terpineol[3]
• Glutathione (reduced and oxidized)[4][5]

2,4,6-trichloroanisole, the chemical primarily responsible for cork taint in wines.

A wine fault or defect is an unpleasant characteristic of a wine often resulting from poor winemaking practices or storage conditions, and leading to wine spoilage. Many of the compounds that cause wine faults are already naturally present in wine but at insufficient concentrations to adversely affect it. However, when the concentration of these compounds greatly exceeds the sensory threshold, they replace or obscure the flavors and aromas that the wine should be expressing (or that the winemaker wants the wine to express). Ultimately the quality of the wine is reduced, making it less appealing and sometimes undrinkable.[12]

The yeast Brettanomyces produces an array of metabolites when growing in wine, some of which are volatile phenolic compounds. Brettanomyces converts p-coumaric acid to 4-vinylphenol via the enzyme cinnamate decarboxylase.[13] 4-Vinylphenol is further reduced to 4-ethylphenol by the enzyme vinyl phenol reductase. 4-Ethylphenol causes a wine fault at a concentration of greater than 140 µg/L. Other compounds produced by Brettanomyces that cause wine faults include 4-ethylguaiacol and isovaleric acid.

Coumaric acid is sometimes added to microbiological media, enabling the positive identification of Brettanomyces by smell.

Geraniol is a by-product of the metabolism of sorbate.

Fusel alcohols are a mixture of several alcohols (chiefly amyl alcohol) produced as a by-product of alcoholic fermentation.

• Beer chemistry
• Food chemistry
• Premature oxidation
• Congener (alcohol), such as tryptophol

• Comprehensive Natural Products II — Chemistry and Biology, chapter 3.26 – Chemistry of Wine, volume 3, pages 1119–1172. Véronique Cheynier, Rémi Schneider, Jean-Michel Salmon and Hélène Fulcrand, doi:10.1016/B978-008045382-8.00088-5

• Wine Chemistry and Biochemistry, by M. Victoria Moreno-Arribas,Carmen Polo and María Carmen Polo, on Google books
• Mass Spectrometry in Grape and Wine Chemistry, by Riccardo Flamini and Pietro Traldi, on Google books
• Antoine de Saporta La Chimie des vins : les vins naturels, les vins manipulés et falsifiés (1889). Google Books